Impact compaction of soil makes use of an impact roller assembly which usually comprises a draw frame and a non-circular lobed compaction roller connected via its axle to the draw frame such as to follow the draw frame when it is propelled, the draw frame being either self propelled or intended for connection to a draught vehicle. The roller, and usually the frame itself, are of robust and extremely heavy construction, having a weight of the order of several tons, so as to provide effective compaction of the underlying soil by successive impacts from the roller, imparted by virtue of its non-circular profile as it rolls along.
While impact roller assemblies provide good soil compaction, problems with the connection between the roller and frame are encountered which arise from the irregular movement of the roller. The irregular movement of the roller includes the jolting movement arising from the non-circular profile of the roller, and other irregular movements arising from uneven or sloping terrain, or from traveling along curves, turning corners, or the like.
Impact roller assemblies of the type in question must, because of the non-circular profile of the roller, provide for relative movement between the roller and frame, in a direction perpendicular to the roller axis. Various types of linkages or connections between the roller and frame have been proposed to permit this relative movement, but, in spite of attempts to make them of durable and robust construction, they suffer from damage and eventual destruction caused by the abovementioned irregular movements, i.e. any movement of the roller relative to the frame not essentially perpendicular to the roller axis. Damage and accelerated wear, arising from the same cause, also takes place to the bearins for the roller axle, and these problems are aggravated by the substantial weights of the frames and rollers involved.
These problems are present in all the impact roller assemblies of the type described known to the applicant to a greater or lesser degree, namely the assemblies of U.S. Pat. Nos. 2,909,106; 3,662,658; 3,788,757; 3,966,346 and 3,950,110; South African Pat. No. 73/2253 and South African published patent applications Nos. 73/2367 and 73/3162. Furthermore, these problems are particulary troublesome when relatively sophisticated linkages or connections between frame and roller are used to reduce the shock loads which are necessarily transmitted from the roller to the frame and draught vehicle, caused by normal movement of the roller perpendicular to its axis, as they are expensive.
The present invention has thus been made in an attempt to eliminate or at least alleviate, the above described problems.